python - 在生成器中捕获异常时保持 try block 较小

Question

当我必须捕获生成器中可能发生的异常时，如何使 try block 尽可能小？

典型的情况是这样的:

for i in g():
  process(i)

如果 g() 可以引发我需要捕获的异常，第一种方法是这样的:

try:
  for i in g():
    process(i)
except SomeException as e:
  pass  # handle exception ...

但是如果它发生在 process(i) 中，这也会捕获 SomeException(这是我不想要的)。

是否有处理这种情况的标准方法？某种模式？

我正在寻找的是这样的:

try:

  for i in g():

except SomeException as e:
  pass  # handle exception ...

    process(i)

(但这当然是句法上的废话。)

Answer 1

您可以转换发生在内部 block 中的异常:

class InnerException(Exception):
  pass

try:
  for i in g():
    try:
      process(i)
    except Exception as ex:
      raise InnerException(ex)
except InnerException as ex:
  raise ex.args[0]
except SomeException as e:
  pass  # handle exception ...

另一种选择是编写一个包装g的本地生成器:

def safe_g():
  try:
    for i in g():
      yield i
  except SomeException as e:
    pass  # handle exception ...
for i in safe_g():
  process(i)